Manually opening TCP ports

[Siraj Shaikh]

Hello

I am just wondering if there is a utility (or any feature in
ubuntu/Linux) that allows me to manually open a TCP port on a machine.
I am looking for a way that could either allow me to open ALL or many
TCP ports on a machine.

Also, is there any way of running a service on more than a single
port, or on all or many ports?

Thanks